Stabilized gasoline



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Robert H. Rosenwal Chicago, lill., assignors to Universal Oil Products ompany, Chicago, mi., a corporation of Delaware @riginal application dpr 205,356, now Patent No. hividcd and this application April 8, 1941, Serial d Claims.

This application is a division of our co-pendng application Serial No. 205,356 filed April 30, i938, now Patent No. 2,250,501V of July 29, 1941.

This invention relates more particularly to a irocess of treatment applicable to lower boiling Fractions of cracked distillates within the gaso- .ine range although it is also applicable to heavier listlllates produced by the fractionation of :racked products and to corresponding fractions from the primary distillation of `crude petroleums :vr other hydrocarbonaceous materials such as coal and shale.

A The process is concerned specically with the use of certain denite types of inhibitors to materially arrest the deterioration to which hydrocarbon distillates containing appreciable quantities oi olenic and other unsaturated hydrocarbons are subject. The art of using inhibitors in unstable gasolines is now one of comparatively longstanding and a large number of individual compounds and classes of compounds have been developed for practical use, all of which apparently possess the characteristic of being more or less readily oxidizable so that the peroxidic compounds which are primarily formed .when olefincontaining gasolines are in contact with .air or other oxidizing gas mixtures are decomposed and the sequence of the chain reactions leading to the formation of higher boiling polymers and resinous products which cause the deterioration of the gasoline in respect to color,`gum content, and antiknock value is stopped for a time depending upon the emclency oi the inhibitor, the' degree of unsaturation oi the oil and the extent v4of its exposure.

It is recognized that the inhibitor art is known to include the use oi such compounds as phenols, amines, and amlnophenols and crude primary products containing these compounds, and no basic claim is made herein to the broad usev oi any oi these classes. The present invention'is specially concerned with a limited group ol compounds which have been found topossess exceptionally good inhibiting potency -combined with resistance to accidental removal by contact with water or caustic soda which occurs at many points in the storage systems oi oil reneries.

il 30, 1938, Serial No. 2,250,501, .ll'ulyA 29, 1941.

(Cl. M-S) aminophenol:

lin one specic embodiment thepresent invention comprises the treatment of unstable gasolines, particularly cracked gasolines, to materially arrest the deterioration thereof by adding to said gasolinas relatively small percentages of N- methyl-N-axnyl aminophenols. The alkyl groups may be of a normal or branched character and the substituted amino group may be in the ortho. meta, or para position with respect to the hydroxyl group although in general the compounds oi greater potency fall within the general class of those oi the para substituted variety.

We have shown as a result of considerable number of experiments in which diierently substituted alkyl aminophenols were tested that greater advantages are gained by utilizing as inhibitors alkyl aminophenols in which there is substitution of both amino hydrogens by different alkyl groups over utilizing those characterized by substitution with identical groups or by substitution of one amino hydrogen with one group even though the total number of carbon atoms in the substituting groups is the same in all cases. The

advantages gained include greater inhibiting poamino hydrogens with the desired alkyl groups.

These step-wise substitutions are made generally by the interaction of molal proportions of an amino phenol'with an alkyl chloride or an alkyl sulfate using an alkaline condensing agent according to the following equations which show the manufacture of N-methyl-N-iso-amyl-pn-N-n H-N-icui Amino phenol isoamyl chloride N-so-amyl-p-amino phenol H H O 0 Methyl chloride scope of the invention, the method shown being denitely applicable to the manufacture oi other similar compounds byl varying the alkyl groups in the reactants according to their relative molecular Weights.

To prepare N-n-octyl-N-methyl-p-aminopheno1, the mixture tabulated below was reuxed for l2 hours under atmospheric pressure.

preservation of color or other specific properties.

I'he following tabulation includes one set oi data obtained in connection with the type of compounds which characterize the present invention. This set of data includes the effect on the copper dish gums and the oxygen bomb stability of a gasoline to which 0.01% of the inhibitors were added.

Copper dish gum, Qxgen bomb stability, Percent removed Eectivo mg.ll cc. 1n uction period, mm. yinhibitor mth) Orig Water Caustic Ori Water Caustic Water Caustic wash wash g wash wash wash wash Original ga oline 37 218 105 85 85 75 N-methyl-N-butyl-p-aminophenoi l. 78 4 7 25 325 290 105 l5 87 N-mcthyi-N-isoamybpaminophenol 1. 51 7 15 8 320 285 105 l5 B7 N-mcthyl-N-octylophenol l. 7 7 l0 335 330 310 0 6 N-methyl-N-Iaury -p-aminophenol. 0. 50 12 9 13 390 425 405 0 0 Parts by weight '20 The effective inhibitor ratio given in column 1 of Methyl-p-aminophenol sulfate 45 the tabulation indicates the relative value of the Sodium bicarbonate 52 compounds as inhibitors. The values were subn-Octyl bromide d5 stantially the same when calculated on a molal Ethyl almhol 200 basis although a slight decrease was observable 2;, as the molecular weight increased. It will be After the period of digestion the total reactants were poured into water and the aqueous and oil layers were extracted with a small volume of ether. Ether extracts were then heated to volatilize the ether and then distilled under an absolute pressure of 4 mm. oi mercury. The primary distillation gave the results shown below Fraction I 2.5 parts by weight Boiling range 120-167 C.

Fraction 1I i' 32.9 parts by weight Boiling range 16B-170 C.

Residue 5.0 parts by weight Redistillation of Fraction H which corresponded to a 70% yield of the desired compound showed a constant boiling point of 163 C.

'Ihe amounts oi the present classes of compounds which are necessary to properly inhibit the deterioration of unstable gasolines will obviously depend upon the instability of the particular gasoline at hand and the potency of the individual compound selected. As a rule it is seldom necessary to employ more than 0.1% of any of the inhibiting compounds and usually Percentages of the order of 0.01% are sumcient. Since the present compounds are considerably more soluble in gasoline than those in which the alkyl groups are the same, the addition of the necessary small amounts to gasoline contained in large storage tanks is more simple and more easily edected than when inhibitors oi' lesser solubility are employed in which cases it is frequently necessary to employ a. long period of mechanical mixing or an auxiliary solvent to assist in the dispersion of the inhibiting compounds. In the present instance a minimum of mixing is required and solvents are not necessary. In addition, owing to the relatively low water and alkali solubility of the preferred compounds, they may be used in gasolines which are not dry or which are stored over water or alkali to prevent corrosion of the tank bottoms. These inhibitors may be also employed in conjunction with other compounds of specic character such as the dyes which are frequently used to mash the slightly yellow tinge characteristic of cracired gasolines, with various types of antiimock compounds such as tetra ethyl lead and with spe types of inhibitors which are directed to seen from the table that the higher molecular weight compounds were substantially unaffected by water or caustic washing `since there was no material change in the copper dish gum or the oxygen bomb stability of the gasolines to which they were added.

The attached curves designated as Figure I are introduced to exemplify the more general aspects of the invention. These curves were made up to indicate the data obtained in a large number of experiments. Referring to the figure. it will be seen that curve #1 shows the variation of the eective inhibitor ratio with the total carbon atoms in substituting groups oi monoalkyl substituted aminophenols. Curve #2 shows the same relationship when di-alkyl substituted compounds are considered in which the substituting groups are the same. Curve #3 which it will be observed is higher than the other two at all points below 18 carbon atoms shows graphically ,the data obtained with mixed alkyl substituted aminophenols. From this data it is ob- 4.viius that the most effective inhibitors are those di-substituted aminophenols in which the substituting groups are diierent.

We claim asour invention:

1. A processifor the treatment of gasolinas subject to deterioration of their desirable properties on storage, which comprises adding thereto amounts of N-methyl-N-amyl-aminophenols equal to less than 0.1% by weight of said gasoline.

2. A process for the treatment oi gasolinas subject to deterioration of their desirable properties on storage, which comprises adding thereto amounts of N-methyl-N-amyl-p-aminophenol equal to less than that 0.1% by weight of said gasoline.

3. A process for the treatment of cracked gasolines subject to deterioration of their desirable properties on storage, which comprises adding thereto amounts of N-methyl-N-amyl-paminophenol equal to less than 0.1% by weight of said gasoline.

e. Motor fuel comprising unstable gasoline containing a relatively small amount of N-methyl-N-amyl-p-aminophenol.

ROBERT H. ROSENVVAID. JOSEPH A. C 

